This book is the fruit of several years of teamwork research and specifically with an analysis of the Ummo documents. It attempts to give a clear and coherent reading of the UFO and Crop Circle phenomena, from an entirely new perspective: An unprecedented inquiry into the origins and purpose of Crop Circles; A panorama of our alien space visitors, based on the crossing of thousands of documents; A Manifesto for the Recognition of Exocivilizations; The presentation of a revolutionary cosmology and of a unified physics theory; The secret of how UFOs move within the framework of a twin cosmology; Patents for antigravitational space engines from a perfectly terrestrial origin; An extraterrestrial Cosmobiophysics; The first deciphering of an extraterrestrial language; About a hundred 3D pictures and explanatory diagrams. The author of PRESENCE approaches ufology based on documents allegedly or proven to be of extraterrestrial origin, more specifically those of Ummo origin as well as the Atienza file. Fundamentally, the point is to present as faithfully as possible the point of view of the exocivilizations that are observing and visiting us. Their culture and cosmology had never been described in any detail by any publisher before. The way UFO s are powered has fueled a great number of studies and hypotheses, of all sorts. Yet here, not only is the principle behind it fully explained, but furthermore, we refer to terrestrial patents relative to the antigravitational levitation unknown by the general public. The first unscrambling and the Denocla method to decypher the alien Ummo language have been precious for us in many areas. Finally, it was also necessary to produce a certain number of explanatory diagrams related to the Ummomen technology and cosmology. In other words, Presence expresses a point of view and a culture coming from outer space. However unnerving it might seem, it is also fascinating. It opens up perspectives that were unheard of in many disciplines: aerospace, scientific, cosmological, exobiological, philosophical etc.